Prior art references disclose position location, tracking and communication devices. Exemplary prior art includes: U.S. Pat. Nos. 6,865,395, 6,889,135, 6,879,584, 6,876,859, 6,876,310 and 6,842,617. From the prior art it is known that it is often desired, and sometimes necessary, to know the position, that is, the location of a wireless user. For example, the US Federal Communications Commission (FCC) has ordered an enhanced emergency 911 (emergency 911 or enhanced emergency E-911) wireless service that requires the location of a wireless terminal (e.g., a cellular phone) to be provided to a Public Safety Answering Point (PSAP) each time a 911 call is made from the terminal. The recognized need for improved personal security and emergency response capability has been documented in the prior art. In situations where an individual is injured, lost, or abducted, immediate notification of an emergency situation including location of the emergency to a local law enforcement or emergency response organization is required to maintain the safety of the individual and to mitigate or avoid severe and or tragic situations.
In addition to emergency situations, there is also a recognized need for improved personal healthcare and in particular patient monitor and other diagnostic systems. Patients are often confined in a fixed area to cabled (or tethered) monitoring equipment. An illustrative, cited prior art reference, published by Balsa, N.: “Designing wireless interfaces for patient monitoring equipment”, RF Design Magazine April 2005, highlights that recent advances in wireless technologies now make it possible to free patients from their equipment, allowing greater freedom and even making possible monitoring by their health provider while the patient is on the go. The position of a wireless terminal may be estimated using various techniques including “range-domain” and “position-domain” techniques as well as other techniques and/or combined hybrid techniques.
Acronyms and abbreviations: several terms, acronyms and abbreviations, used in literature, including patents, journal papers, conference publications, books, published standards and reports have the same and/or similar meaning as in the present application. In particular, terms acronyms and abbreviations, used in the prior art Feher et al. patents: U.S. Pat. No. 6.470,055 (the '055 patent), U.S. Pat. Nos. 6,665,348, 6,757,334, 4,567,602 and 5,491,457 are often used in this document. To facilitate comprehension of some of the terms used in the prior art literature, parts of the prior art '055 patent are reviewed in this application. For other prior art terms, acronyms and abbreviations described in the cited references, the references contained in the cited references and other prior art material are applicable. Position determining devices (PDD), also designated as position determining entities (PDE) and position determining transmitters mean devices and transmitters which generate and transmit signals used by receivers and receive processors for location or position determination and/or location or position estimation have been also described in the prior art. Exemplary prior art single chamber pacemaker and/or dual-chamber pacemaker and implantable cardiac stimulation devices are described in exemplary cited U.S. Pat. Nos. 6,539,253 and in 6,907,291.